Organic light-emitting display device

ABSTRACT

An organic light-emitting display device with improved light efficiency includes a plurality of pixel electrodes each corresponding one of at least a first, second, or third pixel; a pixel-defining layer covering an edge and exposing a central portion of the pixel electrodes; an intermediate layer over the pixel electrode and including an emission layer; an opposite electrode over the intermediate layer; and a lens layer over the opposite electrode and including a plurality of condensing lenses each having a circular lower surface. An area of the portion of the pixel electrode exposed by the pixel-defining layer is A, and an area of the lower surface of the condensing lens is B. For the first pixel, a ratio B/A ranges from about 1.34 to about 2.63. For the second pixel, B/A ranges from about 1.43 to about 3.00, For the third pixel, B/A ranges from about 1.30 to about 2.43.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. patentapplication Ser. No. 16/927,944 filed on Jul. 13, 2020, which is acontinuation application of U.S. patent application Ser. No. 16/264,312filed on Jan. 31, 2019 (now U.S. Pat. No. 10,714,539), which is acontinuation application of U.S. patent application Ser. No. 15/605,307filed on May 25, 2017 (now U.S. Pat. No. 10,224,377), which claimspriority under 35 USC § 119 to Korean Patent Application No.10-2016-0085060, filed on Jul. 5, 2016, in the Korean IntellectualProperty Office, the disclosures of which are incorporated herein intheir entirety by reference.

BACKGROUND 1. Field

One or more embodiments relate to an organic light-emitting displaydevice, and more particularly, to an organic light-emitting displaydevice with improved light efficiency.

2. Description of the Related Art

Generally, an organic light-emitting display device includes an organiclight-emitting diode (OLED) having an intermediate layer including anemission layer between two electrodes. In the organic light-emittingdisplay device, it is generally desirable for light generated from theemission layer to be directed toward a user. However, since lightgenerated from the emission layer of the organic light-emitting displaydevice generally travels in a plurality of directions, brightness in afront direction in which the user is located is low.

SUMMARY

One or more embodiments include an organic light-emitting display devicewith improved light efficiency. However, this object is merelyexemplary, and the scope of the inventive concept is not limitedthereto.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the presented embodiments.

According to one or more embodiments, an organic light-emitting displaydevice includes: a plurality of pixel electrodes, each corresponding toone of at least a first pixel, a second pixel, and a third pixel; apixel-defining layer covering an edge of each of the pixel electrodesand exposing a central portion of each of the pixel electrodes; anintermediate layer over the pixel electrode, the intermediate layercomprising an emission layer; an opposite electrode over theintermediate layer; and a lens layer over the opposite electrode, thelens layer comprising a plurality of condensing lenses each having acircular lower surface. An area of the portion of a pixel electrodecorresponding to the first pixel and exposed by the pixel-defining layeris Ar; an area of the lower surface of a condensing lens over the firstpixel is Br; and the ratio Br/Ar ranges from about 1.34 to about 2.63.An area of the portion of a pixel electrode corresponding to the secondpixel and exposed by the pixel-defining layer is Ag; an area of thelower surface of a condensing lens over the second pixel is Bg; and theratio Bg/Ag ranges from about 1.43 to about 3.00. An area of the portionof a pixel electrode corresponding to the third pixel and exposed by thepixel-defining layer is Ab; an area of the lower surface of a condensinglens over the third pixel is Bb; and the ratio Bb/Ab ranges from about1.30 to about 2.43.

When the light emitted from the emission layer is red light, Br/Ar maybe about 1.62, when the light emitted from the emission layer is greenlight, Bg/Ag may be about 1.77, and when the light emitted from theemission layer is blue light, Bb/Ab may be about 1.55.

According to one or more embodiments, a plurality of pixel electrodes,each corresponding to one of at least a red pixel, a green pixel, and ablue pixel; a pixel-defining layer covering an edge of each of the pixelelectrodes and exposing a central portion of each of the pixelelectrodes; an intermediate layer over the pixel electrode, theintermediate layer including an emission layer; an opposite electrodeover the intermediate layer; and a lens layer over the oppositeelectrode, the lens layer comprising a plurality of condensing lenseseach having a quadrangular lower surface. An area of the portion of apixel electrode corresponding to the red pixel and exposed by thepixel-defining layer is Ar; an area of the lower surface of a condensinglens over the red pixel is Br; and the ratio Br/Ar ranges from about1.71 to about 3.36. An area of the portion of a pixel electrodecorresponding to the green pixel and exposed by the pixel-defining layeris Ag; an area of the lower surface of a condensing lens over the greenpixel is Bg; and the ratio Bg/Ag ranges from about 1.83 to about 3.82.An area of the portion of a pixel electrode corresponding to the bluepixel and exposed by the pixel-defining layer is Ab; an area of thelower surface of a condensing lens over the blue pixel is Bb; and theratio Bb/Ab ranges from about 1.66 to about 3.09.

The ratio Br/Ar may be about 2.07; the ratio Bg/Ag may be about 2.26;and the ratio Bb/Ab may be about 1.98.

The lens layer may include a first lens layer and a second lens layerbetween the first lens layer and the opposite electrode, the second lenslayer having a refractive index less than the refractive index of thefirst lens layer.

The second lens layer may include a concave portion concave in adirection toward the opposite electrode, the first lens layer may fillthe concave portion, and an area of the lower surface of the condensinglens may be an area occupied by the concave portion in a surface of thesecond lens layer in a direction to the first lens layer.

The concave portion may have a depth of about ⅖ to about ⅗ of athickness of a non-concave portion of the second lens layer.

The second lens layer may include a photoresist.

The second lens layer may include acrylate.

The first lens layer may include a material cured by irradiation of anultraviolet ray.

The first lens layer or the second lens layer may include siloxane andat least one of zirconium oxide, aluminum oxide, and titanium oxide.

According to one or more embodiments, an organic light-emitting displaydevice includes: a plurality of pixel electrodes, each corresponding toone of at least a red pixel, a green pixel, and a blue pixel; apixel-defining layer covering an edge of each of the pixel electrodesand exposing a central portion of each of the pixel electrodes; anintermediate layer over the pixel electrode, the intermediate layerincluding an emission layer; an opposite electrode over the intermediatelayer; and a lens layer over the opposite electrode, the lens layercomprising a plurality of condensing lenses each having a polygonallower surface. An area of the portion of a pixel electrode correspondingto the red pixel and exposed by the pixel-defining layer is Ar; an areaof the biggest circle that would fit inside the polygon of the lowersurface of a condensing lens over the red pixel is Br; and the ratioBr/Ar ranges from about 1.34 to about 2.63. An area of the portion of apixel electrode corresponding to the green pixel and exposed by thepixel-defining layer is Ag; an area of the biggest circle that would fitinside the polygon of the lower surface of a condensing lens over thegreen pixel is Bg; and the ratio Bg/Ag ranges from about 1.43 to about3.00. An area of the portion of a pixel electrode corresponding to theblue pixel and exposed by the pixel-defining layer is Ab; an area of thebiggest circle that would fit inside the polygon of the lower surface ofa condensing lens over the blue pixel is Bb; and the ratio Bb/Ab rangesfrom about 1.30 to about 2.43.

The ratio Br/Ar may be about 1.62; the ratio Bg/Ag may be about 1.77;and the ratio Bb/Ab may be about 1.55.

The lens layer may include a first lens layer and a second lens layerbetween the first lens layer and the opposite electrode, the second lenslayer having a refractive index less than the refractive index of thefirst lens layer.

The second lens layer may include a plurality of concave portions eachconcave in a direction toward the opposite electrode, the first lenslayer may fill the concave portions, and each of the areas Br, Bg, andBb may be an area of a circle of a maximum size inside a correspondingconcave portion in a surface of the second lens layer in a direction tothe first lens layer.

According to embodiments, an organic light-emitting display device thatimproves light efficiency may be implemented. However, the scope of theinventive concept is not limited by this effect.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects will become apparent and more readilyappreciated from the following description of the embodiments, taken inconjunction with the accompanying drawings in which:

FIG. 1 is a perspective view of a portion of an organic light-emittingdisplay device according to an embodiment;

FIG. 2 is a cross-sectional view of a portion of the organiclight-emitting display device of FIG. 1;

FIG. 3 is a plan view of the lower surface of a condensing lens of theorganic light-emitting display device of FIG. 1;

FIG. 4 is a graph of a brightness ratio in a front direction dependingon the size of a condensing lens in a red sub-pixel;

FIG. 5 is a graph of a brightness ratio in a front direction dependingon the size of a condensing lens in a green sub-pixel;

FIG. 6 is a graph of a brightness ratio in a front direction dependingon the size of a condensing lens in a blue sub-pixel; and

FIG. 7 is a plan view of the lower surface of a condensing lens of anorganic light-emitting display device according to another embodiment.

DETAILED DESCRIPTION

As the inventive concept allows for various changes and numerousembodiments, exemplary embodiments will be illustrated in the drawingsand described in detail in the written description. An effect and acharacteristic of the inventive concept, and a method of accomplishingthese will be apparent when referring to embodiments described withreference to the drawings. This inventive concept may, however, beembodied in many different forms and should not be construed as limitedto the exemplary embodiments set forth herein.

Hereinafter, the inventive concept will be described more fully withreference to the accompanying drawings, in which exemplary embodimentsof the inventive concept are shown. When description is made withreference to the drawings, like reference numerals in the drawingsdenote like or corresponding elements, and repeated description thereofwill be omitted.

As used herein, the term “and/or” includes any and all combinations ofone or more of the associated listed items.

Expressions such as “at least one of” when preceding a list of elements,modify the entire list of elements and do not modify the individualelements of the list.

Sizes of elements in the drawings may be exaggerated for convenience ofexplanation. In other words, since sizes and thicknesses of componentsin the drawings may be arbitrarily illustrated for convenience ofexplanation, the following embodiments are not limited thereto.

In the following examples, the x-axis, the y-axis and the z-axis are notlimited to the three axes of the rectangular coordinate system, and maybe interpreted in a broader sense. For example, the x-axis, the y-axis,and the z-axis may be perpendicular to one another or may representdifferent directions that are not perpendicular to one another.

FIG. 1 is a perspective view of a portion of an organic light-emittingdisplay device according to an embodiment, and FIG. 2 is across-sectional view of a portion of the organic light-emitting displaydevice of FIG. 1.

As illustrated in FIGS. 1 and 2, the organic light-emitting displaydevice includes organic light-emitting diodes (OLEDs) as displayelements. FIG. 2 illustrates that the organic light-emitting displaydevice includes a red OLED 100R, a green OLED 100G, and a blue OLED100B. The red OLED 100R, the green OLED 100G, and the blue OLED 100B maybe understood as sub-pixels of the organic light-emitting displaydevice. That is, it may be understood that the reference numeral 100Rmeans a red sub-pixel, the reference numeral 100G means a greensub-pixel, and the reference numeral 100B means a blue sub-pixel.

Each of the OLEDs includes a pixel electrode, an intermediate layer overthe pixel electrode, the intermediate layer including an emission layer,and an opposite electrode over the intermediate layer. The OLEDs may beover various layers. For example, as illustrated in FIG. 2, the OLEDsmay be over a planarization layer or a protective layer 10.

The pixel electrodes 110R, 110G, and 110B may be (semi) transparentelectrodes or reflective electrodes. In the case in which the pixelelectrodes 110R, 110G, and 110B are the (semi) transparent electrodes,the pixel electrodes 110R, 110G, and 110B may include ITO, IZO, ZnO,In₂O₃, IGO, or AZO, for example. In the case in which the pixelelectrodes 110R, 110G, and 110B are the reflective electrodes, the pixelelectrodes 110R, 110G, and 110B may include a reflective layer includingAg, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, or a compound thereof, etc., anda layer including ITO, IZO, ZnO, In₂O₃, IGO, or AZO. The inventiveconcepts are not limited thereto, and the pixel electrodes 110R, 110G,and 110B may include various materials and may have various structuressuch as a single layer or multiple layers.

Each of the pixel electrodes 110R, 110G, and 110B may be electricallyconnected to a thin film transistor (not shown). For example, the thinfilm transistors may be below the planarization layer or the protectivelayer 10, and the pixel electrodes 110R, 110G, and 110B may beelectrically connected to corresponding thin film transistors,respectively, via contact holes in the planarization layer or theprotective layer 10. In this case, portions of the pixel electrodes110R, 110G, and 110B that correspond to the contact holes may be coveredwith a pixel-defining layer 200.

A portion, not the entire surface, of the pixel electrodes 110R, 110G,and 110B contacts intermediate layers 120R, 120G, and 120B eachincluding an emission layer. That is, the pixel-defining layer 200covers the edge of each of the pixel electrodes 110R, 110G, and 110Bsuch that the central portion of each of the pixel electrodes 110R,110G, and 110B is exposed. The pixel-defining layer 200 defines a pixelby having openings respectively correspond to sub-pixels, that is, byhaving the openings expose the central portions of at least the pixelelectrodes 110R, 110G, and 110B. Also, the pixel-defining layer 200prevents arc, etc. from occurring at the edges of pixel electrodes 110R,110G, and 110B by increasing a distance between the edge of each of thepixel electrodes 110R, 110G, and 110B and the opposite electrode 130over the pixel electrodes 110R, 110G, and 110B. The pixel-defining layer200 may include, for example, an organic material such as polyimide (PI)or hexamethyldisiloxane (HMDSO).

The intermediate layers 120R, 120G, and 120B each including the emissionlayer may include a low molecular material or a polymer material. In thecase in which the intermediate layers 120R, 120G, and 120B include thelow molecular material, the intermediate layers 120R, 120G, and 120B mayhave a structure in which a hole injection layer (HIL), a hole transportlayer (HTL), an emission layer (EML), an electron transport layer (ETL),an electron injection layer (EIL), etc. are stacked in a single orcomposite structure. The intermediate layers 120R, 120G, and 120B mayinclude various organic materials such as copper phthalocyanine (CuPc),N,N′-Di(naphthalene-1-yl)-N,N′-diphenyl-benzidine (NPB), and/ortris-8-hydroxyquinoline aluminum (Alq3). These layers may be formed byusing a vacuum deposition method.

In the case in which the intermediate layers 120R, 120G, and 120Binclude the polymer material, the intermediate layers 120R, 120G, and120B may generally have a structure including an HTL and an EML. In thiscase, the HTL may include a PEDOT, and the EML may include a polymermaterial such as a poly-phenylenevinylene (PPV)-based material and apolyfluorene-based material. The intermediate layers 120R, 120G, and120B may be formed by using screen printing, an inkjet printing method,or laser induced thermal imaging (LITI), etc.

Though FIG. 2 illustrates that the intermediate layers 120R, 120G, and120B having a multi-layered structure have a shape patterned tocorrespond to the pixel electrodes 110R, 110G, and 110B, some of theintermediate layers 120R, 120G, and 120B having the multi-layeredstructure may have shapes patterned to respectively correspond to thepixel electrodes 110R, 110G, and 110B, and others of the intermediatelayers 120R, 120G, and 120B having the multi-layered structure may haveone body that corresponds to the pixel electrodes 110R, 110G, and 110B.For example, the emission layers may have shapes patterned torespectively correspond to the pixel electrodes 110R, 110G, and 110B.The HTL, the HIL, the ETL, and/or the EIL, etc. may have one body thatcorresponds to the pixel electrodes 110R, 110G, and 110B.

As illustrated in FIG. 2, the opposite electrode 130 may have one bodythat corresponds to a plurality of OLEDs and may correspond to the pixelelectrodes 110R, 110G, and 110B. The opposite electrode 130 may be a(semi) transparent electrode or a reflective electrode. When theopposite electrode 130 is the (semi) transparent electrode, the oppositeelectrode 130 may include a layer including metal having a small workfunction, such as Li, Ca, LiF/Ca, LiF/AI, Al, Ag, Mg, or a compoundthereof, and a (semi) transparent conductive layer including ITO, IZO,ZnO, or In₂O₃, etc. When the opposite electrode 130 is the reflectiveelectrode, the opposite electrode 130 may include a layer including Li,Ca, LiF/Ca, LiF/AI, Al, Ag, Mg, or a compound thereof. The configurationand material of the opposite electrode 130 are not limited thereto andmay be modified variously.

Since the OLEDs 100R, 100G, and 100B may be easily damaged by externalmoisture or oxygen, etc., an encapsulation layer 300 may cover the OLEDs100R, 100G, and 100B and protect the same. As illustrated in FIG. 2, theencapsulation layer 300 may include a first inorganic encapsulationlayer 310, an organic encapsulation layer 320, and a second inorganicencapsulation layer 330.

The first inorganic encapsulation layer 310 may cover the oppositeelectrode 130 and include a silicon oxide, a silicon nitride, and/or asilicon oxynitride, etc. In other embodiments, other layers such as acapping layer may be between the first inorganic encapsulation layer 310and the opposite electrode 130. Since the first inorganic encapsulationlayer 310 is along a structure therebelow, the upper surface of thefirst inorganic encapsulation layer 310 is not planarized as illustratedin FIG. 2. The organic encapsulation layer 320 may cover the firstinorganic encapsulation layer 310. Unlike the first inorganicencapsulation layer 310, the upper surface of the organic encapsulationlayer 320 may be approximately planarized. The organic encapsulationlayer 320 may include at least one of polyethyleneterephthalate (PET),polyethylene naphthalate (PEN), polycarbonate (PC), PI, polyethylenesulphonate, polyoxy methylene (POM), polyacrylate, and HMDSO. The secondinorganic encapsulation layer 330 may cover the organic encapsulationlayer 320 and include a silicon oxide, a silicon nitride, and/or asilicon oxynitride. The second inorganic encapsulation layer 330 mayprevent the organic encapsulation layer 320 from being exposed tooutside by contacting the first inorganic encapsulation layer 310 at theedge of the second inorganic encapsulation layer 330 outside a displayarea.

Since the thin film encapsulation layer 300 includes the first inorganicencapsulation layer 310, the organic encapsulation layer 320, and thesecond inorganic encapsulation layer 330, even when a crack occursinside the encapsulation layer 300, the crack may not be allowed to beconnected between the first inorganic encapsulation layer 310 and theorganic encapsulation layer 320 or between the organic encapsulationlayer 320 and the second inorganic encapsulation layer 330 due to theabove-described multi-layered structure. Through this, forming of a pathvia which external moisture or oxygen, etc. penetrates into the OLEDs100R, 100G, and 100B may be prevented or minimized.

A lens layer 400 is over the opposite electrode 130, for example, on theencapsulation layer 300. In other embodiments, other elements such as atouch electrode layer, etc. for implementing a touchscreen function maybe between the encapsulation layer 300 and the lens layer 400. The lenslayer 400 may include a condensing lens and adjust a light path of lightoccurring from the intermediate layers 120R, 120G, and 1208 eachincluding the emission layer. The lens layer 400 includes a condensinglens and adjusts a light path of light traveling in a lateral direction(a direction between +x direction and +z direction, or a directionbetween −x direction and +z direction) from among light occurring fromthe intermediate layers 120R, 120G, and 1208 each including the emissionlayer, thereby allowing light to approximately travel in a frontdirection (+z direction) in which a user is located. Through this, lightefficiency may improve by improving the brightness of the display devicein the front direction.

The lens layer 400 having the condensing lens may be formed by variousmethods. As illustrated in FIG. 2, the lens layer 400 having thecondensing lens may include a first lens layer 410 and a second lenslayer 420. The second lens layer 420 is between the first lens layer 410and the opposite electrode 130 and has a refractive index less than therefractive index of the first lens layer 410. The condensing lens may beimplemented by using the first lens layer 410 and the second lens layer420 respectively having different refractive indexes.

The second lens layer 420 having a relatively low refractive index isallowed to have a concave portion that is concave in the direction (−zdirection) toward the opposite electrode 130. Also, the first lens layer410 having a relatively high refractive index fills the concave portion.When the first lens layer 410 and the second lens layer 420 are formedas described above, it may be understood that the concave portion of thesecond lens layer 420 and a corresponding portion of the first lenslayer 410 form the condensing lens. Through this, a condensing effect inthe front direction (+z direction) may be allowed to appear by changinga path of light passing through an interface between the first lenslayer 410 and the second lens layer 420 in the concave portion. Thedepth of the concave portion of the second lens layer 420 may be about ⅖to ⅗ of the thickness of a portion of the second lens layer 420 that isnot concaved.

While forming the second lens layer 420, the concave portionsrespectively corresponding to the pixel electrodes 110R, 110G, and 110Bare formed as illustrated in FIG. 2 by coating a material layer for thesecond lens layer 420 and patterning the same. Therefore, when thesecond lens layer 420 is formed by using a photoresist material, aprocess of forming the concave portions may be simplified. If the secondlens layer 420 is formed by using a different material, i.e., not thephotoresist material, the concave portions of the second lens layer 420may be formed via a process of forming a separate photoresist layer overthe material layer for the second lens layer 420, exposing anddeveloping the photoresist layer, and then etching the upper surface ofthe material layer for the second lens layer 420; and after that, thephotoresist layer is removed. Therefore, the process is complicated. Incontrast, when the second lens layer 420 is formed by using aphotoresist material, e.g., the concave portions are formed in the uppersurface of the second lens layer 420 by coating the photoresist materialand exposing and developing the same, the second lens layer 420including the concave portions may be formed via a simple process. Thesecond lens layer 420 may have a refractive index less than that of thefirst lens layer 410, which is formed later, and the photoresist havingthe low refractive index may be acrylate. The second lens layer 420 mayhave a refractive index ranging from about 1.4 to about 1.5.

The first lens layer 410 over the second lens layer 420 may not requireseparate patterning but may have a refractive index greater than that ofthe second lens layer 420. To increase a refractive index, the firstlens layer 410 may include siloxane and at least one of zirconium oxideparticles, aluminum oxide particles, and titanium oxide particles. Thefirst lens layer 410 may have a refractive index of about 1.6 or moreand may be formed by using an inkjet printing method or screen printing,etc.

After the intermediate layers 120R, 120G, and 120B, the oppositeelectrode 130, the encapsulation layer 300, etc. are formed, the lenslayer 400 including the first lens layer 410 and the second lens layer420 may be formed thereon. Damage of the intermediate layers 120R, 120G,and 120B, etc. below the lens layer 400 may be prevented during aprocess of forming the lens layer 400. Particularly, while forming thelens layer 400, a material that does not require heat-curing at hightemperature may be used so that the already formed intermediate layers120R, 120G, and 120B, etc. would not have to undergo heat-curing at hightemperature and avoid being damaged thereby. The above-describedmaterial for the first lens layer 410 and material for the second lenslayer 420 may be materials that allow heat-curing at low temperature ormaterials that allow ultraviolet-curing, so that the intermediate layers120R, 120G, and 120B do not become damaged or influenced.

To increase light-condensing efficiency by using the lens layer 400, thearea of a lower surface of the condensing lens may be suitably adjusted.Here, the area of the lower surface of the condensing lens may beunderstood as an area occupied by a concave portion in the second lenslayer 420 in the direction (+z direction) to the first lens layer 410.First, a case of a condensing lens having a circular lower surfacerepresented by a reference numeral L1 in FIG. 3, which is a plan view ofthe lower surface of a condensing lens of the organic light-emittingdisplay device of FIG. 1, is described.

FIG. 4 is a graph of a brightness ratio in a front direction dependingon the size of a condensing lens in a red sub-pixel 100R. A horizontalaxis in FIG. 4 denotes the diameter of the lower surface of thecondensing lens in unit of μm, and a vertical axis denotes a brightnessratio. Here, the diameter of the lower surface of the condensing lensdenotes a length represented by LL in FIG. 3 and is the diameter of thelower surface of the concave portion of the second lens layer 420 anddenotes a length represented by LAR in FIG. 2.

As the graph of FIG. 4 shows, while the area (refer to a referencenumeral PAR of FIG. 2) of an exposed portion of the red pixel electrode110R that is not covered with the pixel-defining layer 200 is fixed, abrightness ratio in the front direction changes as the diameter of thelower surface of the condensing lens changes. Particularly, when thediameter of the lower surface of the condensing lens is about 20 μm, thegraph is drastically bent; when the diameter of the lower surface of thecondensing lens is about 22 μm, a maximum brightness ratio appears; andwhen the diameter of the lower surface of the condensing lens is about28 μm, the graph is also drastically bent. Therefore, an optimal rangefor the diameter of the lower surface of the condensing lens may beabout 20 μm to about 28 μm. When the diameter of the lower surface ofthe condensing lens is less than about 20 μm or greater than about 28μm, light efficiency drastically deteriorates.

However, the range of the diameter of the lower surface of thecondensing lens that results in optimized light efficiency changesdepending on the area of the exposed portion of the red pixel electrode110R that is not covered with the pixel-defining layer 200. That is,when the area of the exposed portion of the red pixel electrode 110Rthat is not covered with the pixel-defining layer 200 widens, the upperlimit and the lower limit of the diameter of the lower surface of thecondensing lens that result in optimized light efficiency also increase,respectively. When the area of the exposed portion of the red pixelelectrode 110R that is not covered with the pixel-defining layer 200narrows, the upper limit and the lower limit of the diameter of thelower surface of the condensing lens that result in optimized lightefficiency also reduce, respectively. Therefore, determining the optimalrange of the diameter of the lower surface of the condensing lens mayrequire taking into account a ratio of the area of the exposed portionof the red pixel electrode 110R that is not covered with thepixel-defining layer 200 to the area of the lower surface of thecondensing lens.

The graph of FIG. 4 illustrates a case in which the area of the exposedportion of the red pixel electrode 110R that is not covered with thepixel-defining layer 200 is about 233.27 μm². Therefore, assuming thatthe area of the exposed portion of the red pixel electrode 110R that isnot covered with the pixel-defining layer 200 is A, and the area of thelower surface of the condensing lens is B, the ratio B/A of the redsub-pixel 100R may be a value ranging from about 1.34 to about 2.63. Torepresent optimized light efficiency, B/A may be about 1.62.

FIG. 5 is a graph of a brightness ratio in a front direction dependingon the size of a condensing lens in the green sub-pixel 100G of FIG. 2.A horizontal axis in FIG. 5 denotes the diameter of the lower surface ofthe condensing lens in unit of μm, and a vertical axis denotes abrightness ratio. Here, the diameter of the lower surface of thecondensing lens denotes a length represented by LL in FIG. 3 and is thediameter of the lower surface of the concave portion of the second lenslayer 420 and denotes a length represented by LAG in FIG. 2.

As the graph of FIG. 5 shows, while the area (refer to a referencenumeral PAG of FIG. 2) of an exposed portion of the green pixelelectrode 110G that is not covered with the pixel-defining layer 200 isfixed, a brightness ratio in the front direction changes as the diameterof the lower surface of the condensing lens changes. Particularly, whenthe diameter of the lower surface of the condensing lens is about 18 μm,the graph is drastically bent; when the diameter of the lower surface ofthe condensing lens is about 20 μm, a maximum brightness ratio appears;and when the diameter of the lower surface of the condensing lens isabout 26 μm, the graph is also drastically bent. Therefore, an optimalrange for the diameter of the lower surface of the condensing lens maybe about 18 μm to about 26 μm. When the diameter of the lower surface ofthe condensing lens is less than about 18 μm or greater than about 26μm, light efficiency drastically deteriorates.

However, the range of the diameter of the lower surface of thecondensing lens that results in optimized light efficiency changesdepending on the area of the exposed portion of the green pixelelectrode 110G that is not covered with the pixel-defining layer 200.That is, when the area of the exposed portion of the green pixelelectrode 110G that is not covered with the pixel-defining layer 200widens, the upper limit and the lower limit of the diameter of the lowersurface of the condensing lens that result in optimized light efficiencyalso increase, respectively. When the area of the exposed portion of thegreen pixel electrode 110G that is not covered with the pixel-defininglayer 200 narrows, the upper limit and the lower limit of the diameterof the lower surface of the condensing lens that result in optimizedlight efficiency also reduce, respectively. Therefore, determining theoptimal range of the diameter of the lower surface of the condensinglens may require taking into account a ratio of the area of the exposedportion of the green pixel electrode 110G that is not covered with thepixel-defining layer 200 to the area of the lower surface of thecondensing lens.

The graph of FIG. 5 illustrates a case in which the area of the exposedportion of the green pixel electrode 110G that is not covered with thepixel-defining layer 200 is about 176.89 μm². Therefore, assuming thatthe area of the exposed portion of the green pixel electrode 110G thatis not covered with the pixel-defining layer 200 is A, and the area ofthe lower surface of the condensing lens is B, the ratio B/A of thegreen sub-pixel 100G may be a value ranging from about 1.43 to about3.00. To represent optimized light efficiency, B/A may be about 1.77.

FIG. 6 is a graph of a brightness ratio in a front direction dependingon the size of a condensing lens in the blue sub-pixel 100B of FIG. 2. Ahorizontal axis in FIG. 6 denotes the diameter of the lower surface ofthe condensing lens in unit of μm, and a vertical axis denotes abrightness ratio. Here, the diameter of the lower surface of thecondensing lens denotes a length represented by LL in FIG. 3 and is thediameter of the lower surface of the concave portion of the second lenslayer 420 and denotes a length represented by LAB in FIG. 2.

As the graph of FIG. 6 shows, while the area (refer to a referencenumeral PAB of FIG. 2) of an exposed portion of the blue pixel electrode110B that is not covered with the pixel-defining layer 200 is fixed, abrightness ratio in the front direction changes as the diameter of thelower surface of the condensing lens changes. Particularly, when thediameter of the lower surface of the condensing lens is about 22 μm, thegraph is drastically bent; when the diameter of the lower surface of thecondensing lens is about 24 μm, a maximum brightness ratio appears; andwhen the diameter of the lower surface of the condensing lens is about30 μm, the graph is also drastically bent. Therefore, an optimal rangefor the diameter of the lower surface of the condensing lens may beabout 22 μm to about 30 μm. When the diameter of the lower surface ofthe condensing lens is less than about 22 μm or greater than about 30μm, light efficiency drastically deteriorates.

However, the range of the diameter of the lower surface of thecondensing lens that results in optimized light efficiency changesdepending on the area of the exposed portion of the blue pixel electrode110B that is not covered with the pixel-defining layer 200. That is,when the area of the exposed portion of the blue pixel electrode 110Bthat is not covered with the pixel-defining layer 200 widens, the upperlimit and the lower limit of the diameter of the lower surface of thecondensing lens that result in optimized light efficiency also increase,respectively. When the area of the exposed portion of the blue pixelelectrode 110B that is not covered with the pixel-defining layer 200narrows, the upper limit and the lower limit of the diameter of thelower surface of the condensing lens that result in optimized lightefficiency also reduce, respectively. Therefore, determining the optimalrange of the diameter of the lower surface of the condensing lens mayrequire taking into account a ratio of the area of the exposed portionof the blue pixel electrode 110B that is not covered with thepixel-defining layer 200 to the area of the lower surface of thecondensing lens.

The graph of FIG. 6 illustrates a case in which the area of the exposedportion of the blue pixel electrode 110B that is not covered with thepixel-defining layer 200 is about 290.40 μm². Therefore, assuming thatthe area of the exposed portion of the blue pixel electrode 110B that isnot covered with the pixel-defining layer 200 is A, and the area of thelower surface of the condensing lens is B, the ratio B/A of the bluesub-pixel 100B may be a value ranging from about 1.30 to about 2.43. Torepresent optimized light efficiency, B/A may be about 1.55.

Up to now, the case of the condensing lens having the lower surface likethe circle represented by the reference numeral L1 in FIG. 3, which is aplan view of the lower surface of the condensing lens of the organiclight-emitting display device of FIG. 1 has been described. Hereinafter,a case of a condensing lens having a lower surface shape of aquadrangle, specifically, a square represented by a reference numeral L2in FIG. 3, which is a plan view of the lower surface of the condensinglens of the organic light-emitting display device of FIG. 1, isdescribed.

While the area (refer to a reference numeral PAR of FIG. 2) of theexposed portion of the red pixel electrode 110R that is not covered withthe pixel-defining layer 200 is fixed, when the length (a lengthrepresented by LL in FIG. 3) of one side of the lower surface of thecondensing lens having a square lower surface changes, a brightnessratio in the front direction changes. However, it has been revealed thatif the area of the exposed portion of the red pixel electrode 110R thatis not covered with the pixel-defining layer 200 is the same, thebrightness in the front direction is the same regardless of whether thelower surface is a square or a circle, as long as the length (the lengthrepresented by LL in FIG. 3) of one side of the lower surface of thecondensing lens having a square lower surface is the same as thediameter (the length represented by LL in FIG. 3) of the lower surfaceof the condensing lens having a circular lower surface.

That is, under a circumstance in which the area of the exposed portionof the red pixel electrode 110R that is not covered with thepixel-defining layer 200 is fixed as about 233.27 μm², a graph of achange in a brightness ratio in a front direction while changing thelength (the length represented by LL in FIG. 3) of one side of the lowersurface of the condensing lens having a square lower surface is the sameas the graph of FIG. 4, which is a graph of a change in a brightnessratio in a front direction while changing the diameter (the lengthrepresented by LL in FIG. 3) of the condensing lens having a circularlower surface. Even in this case, it has been revealed that when thelength of one side of the lower surface of the condensing lens havingthe square lower surface is about 20 μm, the graph is drastically bent;when the length of one side is about 22 μm, a maximum brightness ratioappears; and when the length of one side is about 28 μm, the graph isalso drastically bent. Therefore, an optimal range for the length of oneside of the lower surface of the condensing lens having the square lowersurface may be about 20 μm to about 28 μm. When the length of one sideof the lower surface of the condensing lens having the square lowersurface is less than about 20 μm or greater than about 28 μm, lightefficiency drastically deteriorates.

Similar to the description above, the range of the length of one side ofthe lower surface of the condensing lens having the square lower surfacethat results in the above-described optimized light efficiency changesdepending on the area of the exposed portion of the red pixel electrode110R that is not covered with the pixel-defining layer 200. That is,when the area of the exposed portion of the red pixel electrode 110Rthat is not covered with the pixel-defining layer 200 widens, the upperlimit and the lower limit of the length of one side of the lower surfaceof the condensing lens having the square lower surface that result inoptimized light efficiency also increase, respectively. When the area ofthe exposed portion of the red pixel electrode 110R that is not coveredwith the pixel-defining layer 200 narrows, the upper limit and the lowerlimit of the length of one side of the lower surface of the condensinglens having the square lower surface that result in optimized lightefficiency also reduce, respectively. Therefore, determining the optimalrange of the length of one side of the lower surface of the condensinglens having the square lower surface may require taking into account aratio of the area of the exposed portion of the red pixel electrode 110Rthat is not covered with the pixel-defining layer 200 to the area of thelower surface of the condensing lens having the square lower surface.

The graph of FIG. 4 illustrates a case in which the area of the exposedportion of the red pixel electrode 110R that is not covered with thepixel-defining layer 200 is about 233.27 μm2. Therefore, assuming thatthe area of the exposed portion of the red pixel electrode 110R that isnot covered with the pixel-defining layer 200 is A, and the area of thelower surface of the condensing lens having the square lower surface isB, the ratio B/A of the red sub-pixel 100R may be a value ranging fromabout 1.71 to about 3.36. To represent optimized light efficiency, B/Amay be about 2.07.

The discussion made for the red sub-pixel 100R is also applicable to thegreen sub-pixel 100G. That is, under a circumstance in which the area ofthe exposed portion of the green pixel electrode 110G that is notcovered with the pixel-defining layer 200 is fixed as about 233.27 μm²,a graph of a change in a brightness ratio in a front direction whilechanging the length (the length represented by LL in FIG. 3) of one sideof the lower surface of the condensing lens having a square lowersurface is the same as the graph of FIG. 5, which is a graph of a changein a brightness ratio in a front direction while changing the diameter(the length represented by LL in FIG. 3) of the condensing lens having acircular lower surface.

Even in this case, it has been revealed that when the length of one sideof the lower surface of the condensing lens having the square lowersurface is about 18 μm, the graph is drastically bent; when the lengthof one side is about 20 μm, a maximum brightness ratio appears; and whenthe length of one side is about 26 μm, the graph is also drasticallybent. Therefore, the length of one side of the lower surface of thecondensing lens having the square lower surface may be about 18 μm toabout 26 μm. When the length of one side of the lower surface of thecondensing lens having the square lower surface is less than about 18 μmor greater than about 26 μm, light efficiency drastically deteriorates.

Similar to the description above, the range of the length of one side ofthe lower surface of the condensing lens having the square lower surfacethat results in the above-described optimized light efficiency changesdepending on the area of the exposed portion of the green pixelelectrode 110G that is not covered with the pixel-defining layer 200.Therefore, determining the optimal range of the length of one side ofthe lower surface of the condensing lens having the square lower surfacemay require taking into account a ratio of the area of the exposedportion of the green pixel electrode 110G that is not covered with thepixel-defining layer 200 to the area of the lower surface of thecondensing lens having the square lower surface.

The graph of FIG. 5 illustrates a case in which the area of the exposedportion of the green pixel electrode 110G that is not covered with thepixel-defining layer 200 is about 176.89 μm². Therefore, assuming thatthe area of the exposed portion of the green pixel electrode 110G thatis not covered with the pixel-defining layer 200 is A, and the area ofthe lower surface of the condensing lens having the square lower surfaceis B, the ratio B/A of the green sub-pixel 100G may be a value rangingfrom about 1.83 to about 3.82. To represent optimized light efficiency,B/A may be about 2.26.

The discussions made for the red sub-pixel 100R and the green sub-pixel100G are also applicable to the blue sub-pixel 100B. That is, under acircumstance in which the area of the exposed portion of the blue pixelelectrode 110B that is not covered with the pixel-defining layer 200 isfixed as about 290.40 μm², a graph of a change in a brightness ratio ina front direction while changing the length (the length represented byLL in FIG. 3) of one side of the lower surface of the condensing lenshaving a square lower surface is the same as the graph of FIG. 6, whichis a graph of a change in a brightness ratio in a front direction whilechanging the diameter (the length represented by LL in FIG. 3) of thecondensing lens having a circular lower surface.

Even in this case, it has been revealed that when the length of one sideof the lower surface of the condensing lens having the square lowersurface is about 22 μm, the graph is drastically bent; when the lengthof one side is about 24 μm, a maximum brightness ratio appears; and whenthe length of one side is about 30 μm, the graph is also drasticallybent. Therefore, the length of one side of the lower surface of thecondensing lens having the square lower surface may be about 22 μm toabout 30 μm. When the length of one side of the lower surface of thecondensing lens having the square lower surface is less than about 22 μmor greater than about 30 μm, light efficiency drastically deteriorates.

Similar to the description above, the range of the length of one side ofthe lower surface of the condensing lens having the square lower surfacethat results in the over-described optimized light efficiency changesdepending on the area of the exposed portion of the blue pixel electrode110B that is not covered with the pixel-defining layer 200. Therefore,determining the optimal range of the length of one side of the lowersurface of the condensing lens having the square lower surface mayrequire taking into account a ratio of the area of the exposed portionof the blue pixel electrode 110B that is not covered with thepixel-defining layer 200 to the area of the lower surface of thecondensing lens having the square lower surface.

The graph of FIG. 6 illustrates a case in which the area of the exposedportion of the blue pixel electrode 110B that is not covered with thepixel-defining layer 200 is about 290.40 μm². Therefore, assuming thatthe area of the exposed portion of the blue pixel electrode 110B that isnot covered with the pixel-defining layer 200 is A, and the area of thelower surface of the condensing lens having the square lower surface isB, the ratio B/A of the blue sub-pixel 100B may be a value ranging fromabout 1.66 to about 3.09. To represent optimized light efficiency, B/Amay be about 1.98.

Up to now, though the case in which the lower surface of the condensinglens is a square or a circle has been described, the embodiments are notlimited thereto.

If the areas of the exposed portions of the red pixel electrode 110Rthat are not covered with the pixel-defining layer 200 are the same asdescribed above, the brightness in the front direction is the sameregardless of whether the lower surface is a square or a circle, as longas the length (the length represented by LL in FIG. 3) of one side ofthe lower surface of the condensing lens having the square lower surfaceis the same as the diameter (the length represented by LL in FIG. 3) ofthe lower surface of the condensing lens having the circular lowersurface. That is, under a circumstance in which the area of the exposedportion of the red pixel electrode 110R that is not covered with thepixel-defining layer 200 is fixed as about 233.27 μm², a graph of achange in a brightness ratio in a front direction while changing thelength (the length represented by LL in FIG. 3) of one side of the lowersurface of the condensing lens having a square lower surface is the sameas the graph of FIG. 4, which is a graph of a change in a brightnessratio in the front direction while changing the diameter (the lengthrepresented by LL in FIG. 3) of the condensing lens having the circularlower surface.

Furthermore, the same/similar description may be made to even a case inwhich the lower surface of a condensing lens included in the lens layer,represented by a reference numeral L3, is a polygon in FIG. 7, which isa plan view of the lower surface of a condensing lens of an organiclight-emitting display device according to another embodiment. That is,under a circumstance in which the area of the exposed portion of the redpixel electrode 110R that is not covered with the pixel-defining layer200 is fixed as about 233.27 μm², when measuring a change in thebrightness ratio in the front direction while changing the size of thepolygon such that the diameter (a length represented by LL in FIG. 7) ofa virtual circle IC (i.e., an incircle or inscribed circle) having amaximum size which may be located inside the polygon changes in thelower surface of the condensing lens, a graph that has the diameter ofthe virtual circle IC of the maximum size as a horizontal axis and abrightness ratio as a vertical axis is the same as the graph of FIG. 4,which is a graph of a change in the brightness ratio in the frontdirection while changing the diameter (the length represented by LL inFIG. 3) of the condensing lens having the circular lower surface.

Likewise, under a circumstance in which the area of the exposed portionof the green pixel electrode 110G that is not covered with thepixel-defining layer 200 is fixed as about 176.89 μm², when measuring achange in the brightness ratio in the front direction while changing thesize of the polygon such that the diameter (the length represented by LLin FIG. 7) of the virtual circle IC having a maximum size which may belocated inside the polygon changes in the lower surface of thecondensing lens having the lower polygonal surface, a graph that has thediameter of the virtual circle IC of the maximum size as a horizontalaxis and a brightness ratio as a vertical axis is the same as the graphof FIG. 5, which is a graph of a change in the brightness ratio in thefront direction while changing the diameter (the length represented byLL in FIG. 3) of the condensing lens having the circular lower surface.Also, under a circumstance in which the area of the exposed portion ofthe blue pixel electrode 110B that is not covered with thepixel-defining layer 200 is fixed as about 290.40 μm², when measuring achange in the brightness ratio in the front direction while changing thesize of the polygon such that the diameter (the length represented by LLin FIG. 7) of the virtual circle IC having a maximum size which may belocated inside the polygon changes in the lower surface of thecondensing lens having the lower polygonal surface, a graph that has thediameter of the virtual circle IC of the maximum size as a horizontalaxis and a brightness ratio as a vertical axis is the same as the graphof FIG. 6, which is a graph of a change in the brightness ratio in thefront direction while changing the diameter (the length represented byLL in FIG. 3) of the condensing lens having the circular lower surface.

Therefore, assuming that the area of the exposed portion of the redpixel electrode 110R that is exposed by the pixel-defining layer 200 isA, and the area of the virtual circle IC having a maximum size that maybe located inside the polygon in the lower surface of the condensinglens having the lower polygonal surface is B, the B/A of the redsub-pixel 100R may be about 1.34 to about 2.63. To represent optimizedlight efficiency, B/A may be 1.62.

In other embodiments, assuming that the area of the exposed portion ofthe green pixel electrode 110G that is exposed by the pixel-defininglayer 200 is A, and the area of the virtual circle IC having a maximumsize that may be located inside the polygon in the lower surface of thecondensing lens having the lower polygonal surface is B, the ratio B/Aof the green sub-pixel 100G may be about 1.43 to about 3.00. Torepresent optimized light efficiency, B/A may be 1.77. Also, in otherembodiments, assuming that the area of the exposed portion of the bluepixel electrode 110B that is exposed by the pixel-defining layer 200 isA, and the area of the virtual circle IC having a maximum size that maybe located inside the polygon in the lower surface of the condensinglens having the lower polygonal surface is B, the ratio B/A of the bluesub-pixel 100B may be about 1.30 to about 2.43. To represent optimizedlight efficiency, B/A may be 1.55.

The descriptions in over embodiments for the refractive index of thefirst lens layer 410 or the second lens layer 420, or the process offorming the first lens layer 410 or the second lens layer 420, ormaterials which may be used for this process, etc. are applicable to thedisplay device including the condensing lens having the lower polygonalsurface as described above.

Though the inventive concept has been described with reference to theembodiments illustrated in the drawings, this is merely exemplary, andit will be understood by those of ordinary skill in the art that variouschanges in form and details and equivalents thereof may be made thereinwithout departing from the spirit and scope of the inventive concept asdefined by the following claims.

What is claimed is:
 1. An organic light-emitting display devicecomprising: a plurality of pixel electrodes, each corresponding to oneof at least a first pixel, a second pixel, and a third pixel; apixel-defining layer covering an edge of each of the pixel electrodesand exposing a central portion of each of the pixel electrodes; anintermediate layer over the pixel electrode, the intermediate layercomprising an emission layer; an opposite electrode over theintermediate layer; an encapsulation layer over the opposite electrode,the encapsulation layer comprising at least one inorganic encapsulationlayer and at least one organic encapsulation layer; a touch electrodelayer disposed between the encapsulation layer and a lens layer; and thelens layer directly on the touch electrode layer, the lens layercomprising a first lens layer and a second lens layer between the firstlens layer and the touch electrode layer, the second lens layer having arefractive index less than the refractive index of the first lens layer,wherein the second lens layer comprises a first portion concave in adirection toward the encapsulation layer and a second portion locatedoutside the first portion, and the first lens layer comprises a thirdportion filling the first portion and a fourth portion located outsidethe third portion, wherein each of the first portion and the thirdportion overlaps the central portion of each of the pixel electrodesexposed by the pixel-defining layer, and wherein each of the secondportion and the fourth portion overlaps the pixel defining layer.
 2. Thedisplay device of claim 1, wherein a thickness of the third portion isgreater than a thickness of the first portion.
 3. The display device ofclaim 1, wherein a thickness of the second portion is greater than athickness of the fourth portion.
 4. The display device of claim 1, eachof the second portion and the fourth portion does not overlap thecentral portion of each of the pixel electrodes exposed by thepixel-defining layer.
 5. The display device of claim 1, wherein thesecond lens layer comprises a photoresist.
 6. The display device ofclaim 1, wherein the second lens layer comprises acrylate.
 7. Thedisplay device of claim 1, wherein the first lens layer or the secondlens layer comprises a material cured by irradiation of an ultravioletray.
 8. The display device of claim 1, wherein the first lens layercomprises siloxane and at least one of zirconium oxide, aluminum oxide,and titanium oxide.
 9. The display device of claim 1, wherein the lenslayer comprises a plurality of condensing lenses and each of theplurality of condensing lenses has a circular lower surface.
 10. Thedisplay device of claim 9, wherein an area of the central portion of apixel electrode corresponding to the first pixel and exposed by thepixel-defining layer is Ar, an area of the lower surface of a condensinglens over the first pixel is Br, and the ratio Br/Ar ranges from about1.34 to about 2.63; wherein an area of the central portion of a pixelelectrode corresponding to the second pixel and exposed by thepixel-defining layer is Ag, an area of the lower surface of a condensinglens over the second pixel is Bg, and the ratio Bg/Ag ranges from about1.43 to about 3.00; and wherein an area of the central portion of apixel electrode corresponding to the third pixel and exposed by thepixel-defining layer is Ab, an area of the lower surface of a condensinglens over the third pixel is Bb, and the ratio Bb/Ab ranges from about1.30 to about 2.43.
 11. The display device of claim 10, wherein theratio Br/Ar is about 1.62, the ratio Bg/Ag is about 1.77, and the ratioBb/Ab is about 1.55.
 12. The display device of claim 1, wherein the lenslayer comprises a plurality of condensing lenses and each of theplurality of condensing lenses has a quadrangular lower surface.
 13. Thedisplay device of claim 12, wherein an area of the central portion of apixel electrode corresponding to the first pixel and exposed by thepixel-defining layer is Ar, an area of the lower surface of a condensinglens over the first pixel is Br, and the ratio Br/Ar ranges from about1.71 to about 3.36; wherein an area of the central portion of a pixelelectrode corresponding to the second pixel and exposed by thepixel-defining layer is Ag, an area of the lower surface of a condensinglens over the second pixel is Bg, and the ratio Bg/Ag ranges from about1.83 to about 3.82; and wherein an area of the central portion of apixel electrode corresponding to the third pixel and exposed by thepixel-defining layer is Ab, an area of the lower surface of a condensinglens over the third pixel is Bb, and the ratio Bb/Ab ranges from about1.66 to about 3.09.
 14. The display device of claim 13, wherein theratio Br/Ar is about 2.07, the ratio Bg/Ag is about 2.26, and the ratioBb/Ab is about 1.98.
 15. The display device of claim 1, wherein the lenslayer comprises a plurality of condensing lenses and each of theplurality of condensing lenses has a polygonal lower surface.
 16. Thedisplay device of claim 15, wherein an area of the central portion of apixel electrode corresponding to the first pixel and exposed by thepixel-defining layer is Ar, an area of a biggest circle that would fitinside the polygonal lower surface of a condensing lens over the firstpixel is Br, and the ratio Br/Ar ranges from about 1.34 to about 2.63;wherein an area of the central portion of a pixel electrodecorresponding to the second pixel and exposed by the pixel-defininglayer is Ag, an area of a biggest circle that would fit inside thepolygonal lower surface of a condensing lens over the second pixel isBg, and the ratio Bg/Ag ranges from about 1.43 to about 3.00; andwherein an area of the central portion of a pixel electrodecorresponding to the third pixel and exposed by the pixel-defining layeris Ab, an area of a biggest circle that would fit inside the polygonallower surface of a condensing lens over the third pixel is Bb, and theratio Bb/Ab ranges from about 1.30 to about 2.43.
 17. The display deviceof claim 16, wherein the ratio Br/Ar is about 1.62, the ratio Bg/Ag isabout 1.77, and the ratio Bb/Ab is about 1.55.
 18. An organiclight-emitting display device comprising: a plurality of pixelelectrodes; a pixel-defining layer covering an edge of each of the pixelelectrodes and exposing a central portion of each of the pixelelectrodes; an intermediate layer over the pixel electrode, theintermediate layer comprising an emission layer; an opposite electrodeover the intermediate layer; an encapsulation layer over the oppositeelectrode, the encapsulation layer comprising at least one inorganicencapsulation layer and at least one organic encapsulation layer; atouch electrode layer disposed between the encapsulation layer and alens layer; and the lens layer over the touch electrode layer, the lenslayer comprising a first lens layer and a second lens layer between thefirst lens layer and the touch electrode layer, the second lens layerhaving a refractive index less than the refractive index of the firstlens layer, wherein the second lens layer comprises a first portionconcave in a direction toward the encapsulation layer and a secondportion located outside the first portion, and the first lens layercomprises a third portion filling the first portion and a fourth portionlocated outside the third portion, wherein each of the second portionand the fourth portion overlaps the pixel-defining layer, and whereineach of the second portion and the fourth portion does not overlap thecentral portion of each of the pixel electrodes exposed by thepixel-defining layer.
 19. The display device of claim 18, wherein thelens layer comprises a plurality of condensing lenses and each of theplurality of pixel electrodes corresponds to one of at least a firstpixel, a second pixel, and a third pixel; wherein each of the pluralityof condensing lenses has a circular lower surface; wherein an area ofthe central portion of a pixel electrode corresponding to the firstpixel and exposed by the pixel-defining layer is Ar, an area of thelower surface of a condensing lens over the first pixel is Br, and theratio Br/Ar ranges from about 1.34 to about 2.63; wherein an area of thecentral portion of a pixel electrode corresponding to the second pixeland exposed by the pixel-defining layer is Ag, an area of the lowersurface of a condensing lens over the second pixel is Bg, and the ratioBg/Ag ranges from about 1.43 to about 3.00; and wherein an area of thecentral portion of a pixel electrode corresponding to the third pixeland exposed by the pixel-defining layer is Ab, an area of the lowersurface of a condensing lens over the third pixel is Bb, and the ratioBb/Ab ranges from about 1.30 to about 2.43.
 20. The display device ofclaim 18, wherein the lens layer comprises a plurality of condensinglenses and each of the plurality of pixel electrodes corresponds to oneof at least a first pixel, a second pixel, and a third pixel; whereineach of the plurality of condensing lenses has a quadrangular lowersurface; wherein an area of the central portion of a pixel electrodecorresponding to the first pixel and exposed by the pixel-defining layeris Ar, an area of the lower surface of a condensing lens over the firstpixel is Br, and the ratio Br/Ar ranges from about 1.71 to about 3.36;wherein an area of the central portion of a pixel electrodecorresponding to the second pixel and exposed by the pixel-defininglayer is Ag, an area of the lower surface of a condensing lens over thesecond pixel is Bg, and the ratio Bg/Ag ranges from about 1.83 to about3.82; and wherein an area of the central portion of a pixel electrodecorresponding to the third pixel and exposed by the pixel-defining layeris Ab, an area of the lower surface of a condensing lens over the thirdpixel is Bb, and the ratio Bb/Ab ranges from about 1.66 to about 3.09.21. The display device of claim 18, wherein the lens layer comprises aplurality of condensing lenses and each of the plurality of pixelelectrodes corresponds to one of at least a first pixel, a second pixel,and a third pixel; wherein each of the plurality of condensing lenseshas a polygonal lower surface; wherein an area of the central portion ofa pixel electrode corresponding to the first pixel and exposed by thepixel-defining layer is Ar, an area of a biggest circle that would fitinside the polygonal lower surface of a condensing lens over the firstpixel is Br, and the ratio Br/Ar ranges from about 1.34 to about 2.63;wherein an area of the central portion of a pixel electrodecorresponding to the second pixel and exposed by the pixel-defininglayer is Ag, an area of a biggest circle that would fit inside thepolygonal lower surface of a condensing lens over the second pixel isBg, and the ratio Bg/Ag ranges from about 1.43 to about 3.00; andwherein an area of the central portion of a pixel electrodecorresponding to the third pixel and exposed by the pixel-defining layeris Ab, an area of a biggest circle that would fit inside the polygonallower surface of a condensing lens over the third pixel is Bb, and theratio Bb/Ab ranges from about 1.30 to about 2.43.